To maintain the security essential for shipping providers, plans for DHL's new 290,000-sq.-ft., Allentown, Pa., distribution facility called for 3,450 linear feet of retaining wall topped by chain link fencing along the perimeter of the 72-acre site. Accordingly, Strata Systems' Sleeve-It 1224R offered a solution for installation of a chain link fence above the walls, addressing a primary concern of the wall contractor and construction manager.
It is rarely understood by the client that fencing cannot be installed on top of perimeter walls without careful design considerations, asserts Andre De Carville, vice president of Pickering Valley Landscape, Inc. The grading plan noted a fence above every wall, but did not provide structural detail showing how to integrate our work with that of the fence contractor.
While segmental retaining walls (SRW) Û typically, dry stacked block face and geosynthetic reinforcement (Geogrid) implemented in combination to form a retention system Û can hold back steep slopes and handle heavy loads, the dry stacked wall face has minimal resistance to overturning in the upper two or three courses when a point load is applied to the block. That is precisely what occurs when a load is placed on a fence post in close proximity to the wall face. In addition, tearing through the embedded soil reinforcement behind the wall with an auger can diminish the integrity of both wall and fence structures.
When contacted by the DHL project builders, Strata Systems proposed using its Sleeve-It 1224R, a pre-engineered product whose fence-ready and code-compliant design was said to resolve issues confronting the construction team. Strata provided for the engineer of record test reports as well as additional calculations to verify that the Sleeve-It system meets or exceeds building code requirements for railings along the sides of elevated walking surfaces. Moreover, a Strata technical representative was put at the contractor's disposal for on-site consultation.
A tight timetable further prompted selection of Sleeve-It 1224R: only 10 days were available from the bid award date to provide a final wall design, and 120 days were scheduled from ground breaking to completion of a fully operational new facility. Says wall design engineer Bart Shippee P.E., We recommended use of the pre-engineered Sleeve-It system to the construction manager, Opus Corp., for integrating chain link fence with SRWs, as the product test data translates exceptionally well for a 6-ft.-tall chain link fence with 10-ft. post spacing, addressing the IBC load criteria for railings in commercial applications.
Adds Pickering Field Supervisor Ron Buchanan, Although this was our first project with Sleeve-It, there was virtually no learning curve, so our wall production rate was not slowed at all.
Sleeve-It is stocked by the pallet and sold by the box. I was able to fit two pallets in the back of my pickup, notes Buchanan, rather than pulling a trailer with 12-ft. sections of ADS pipe.
In all, over 350 Sleeve-It units were installed during wall construction. Components typically are preassembled at the material-staging area for the wall, then set in place with desired post spacing when the wall has reached a level approximately 24 inches shy of its full height.
Once the wall was erected, the fence installer arrived to complete perimeter fencing. We showed up ready to auger holes, and much to our surprise, the holes were already there, reports Scott Risbon of Earthcare Landscaping Inc. There was even a lid on every one that kept the topsoil from filling the holes during several rain storms after the wall was built.
Using Sleeve-It technology eliminated the need for a 36-in. offset of the fence on top of the wall. In contrast to traditional methods of integrating a railing at the wall face that could have added two to three times the cost to this portion of the job, Strata Systems contends, that 3-ft. real estate savings translated into a total area savings of 10,000 square feet for the entire project. The end result was a well secured facility, the manufacturer adds, completed on time and within budget.